Pioneer VSX-918V-S Service Manual page 37

5
QQ
USB Troubleshooting
3 7 63 1515 0
Step 1: Connectors
CN401, CN1, CN2, CN3*, CN7**
Are
the connectors
securely inserted
?
To STEP 2
Step 2: Power supply
CN1 (pins 8, 9)
1
Is
the voltage
5 V ?
Yes
TE
L 13942296513
2
IC1 (pins 3, 4)
Is
the voltage
5 V ?
Yes
3
IC1 (pin 5)
Is
the voltage
3.3 V ?
Yes
4
IC351 (pin 20)
Is
the voltage
5 V ?
www
Yes
.
5
http://www.xiaoyu163.com
No
Insert the connectors
securely.
Yes
5 V input (For internal circuit)
Is there
No
any loose
connection
of CN1?
Check the POWER
Yes
PACK Assy.
To STEP 1
3.3 V Regulator IC input
No
Check the patterns in
the path.
3.3 V Reg. output
Is IC1
No
abnormally
hot?
Yes
The output and GND may be
short-circuited. Check the path
between them.
3 V to 5 V Converter
No Check the parts and
patterns in the path.
x ao
y
i
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6
8
5
Q401 (emitter)
the voltage
3.3 V ?
6
Q401 (collector)
the voltage
3.3 V ?
No
7
IC402 (pins 1, 3)
the voltage
3.3 V ?
Q Q
3 6 7 1 3
8
IC462 (pins 37, 47) FLASH ROM
the voltage
3.3 V ?
9
IC461 (pins 1,3,9,14,27,43,49) SDRAM
No
the voltage
Replace IC1.
3.3 V ?
10
IC481 (pins 1, 40) Co-Processor
the voltage
3.3 V ?
u163
.
VSX-918V-K
6
7
2 9 9 4 2 8
* VSX-918V (AWX8977)
** VSX-818V (AWX9164)
3.3 V Local switch
Is
No
Check the parts and
patterns in the path.
Yes
3.3 V Local switch operation
Is
Is the base of
No
Q402 High? (about 5 V)
[USBPWR]
Yes
Yes
Replace Q401, or check the
circuit around Q401 and Q402.
1.8 V Regulator IC input
Is
No Check the patterns in
the path.
1 5 0 5 8 2 9 9 4
Yes
Is
No Check the parts and
patterns in the path.
Yes
Is
No
Check the parts and
patterns in the path.
Yes
Is
No Check the parts and
patterns in the path.
Yes
m
co
A
7
8
9 9
A
B
No
Check CN3*, CN7**
pin 17.
[USB POWER]
C
2 8 9 9
D
E
F
37
8